Assessing the influence of groundwater storage trends on internal migrations and conflicts

Water resources are extremely important for the health of ecosystems, human life, and for a large part of human activities. Like many natural resources, their quantity and quality are imperiled by many threats, including pollution, anthropogenic overexploitation, and ongoing climate change, with clear consequences for society and nature. In particular groundwater, a resource that has not yet been extensively studied due to the difficulty in measuring it directly, is intimately linked to the health of ecosystems and provides many direct benefits to economic, industrial, and domestic human activities. The purpose of this thesis was to assess how quantity and variability of ground water resources, obtained from the simulation of ISIMIP3a model, are associated with human security as measured by conflict occurrence and internal migration. To this end, two different empirical approaches were used. The first approach consisted of a simple linear regression with fixed effects (administrative region and year) between some variables constructed from the amount of groundwater and, separately, the number of internal migrants and the number of conflicts for each region. As a second approach, two random forest models, a regression and a classification, were used in order to search for the possible presence of nonlinear relationships respectively for migrations and conflicts. In order to explore the heterogeneities, countries were classified into different categories by their geographical and socioeconomic characteristics. Based on the linear regression, it is found that the variations in ground water resources contribute to both an increase and a decrease in conflict and migration depending on a context. An additional finding from the random forest methods indicates that the relationships are nonlinear, although still within the subdivisions of the various classes.